function a = matnorm1(B,n)
%UNTITLED 求矩阵无穷范数
%   此处显示详细说明
k = 1;
x = zeros(n,1);
x(:) = 1/n;
while k == 1
    w = B*x;
    v = sign(w);
    z = B'*v;
    if max(abs(z)) <= z'*x
        b = sum(abs(w));
        k = 0;
    else
        x(1:n) = 0;
        [~,j] = max(abs(z));
        x(j) = 1;
        k = 1;
    end
end
a = b;
end

